Endoscopic skull base surgeries

1. Endoscopic skull base surgeries
Dr Ajay kumar
PDT NEUROSURGERY BIN
KOLKATA

2. • Skull base surgery has been transformed by the
development of endoscopic endonasal surgery. These
techniques were initially developed for paranasal sinus
surgery, but their indications have been gradually
extended to include endoscopic resection of pituitary
tumours, and then lesions of the clivus, olfactory cleft,
planum sphenoidale, the petrous apex, or
infratemporal fossa.
• The major advantage of the endoscopic endonasal
approach is that it provides direct anatomical access to
a large number of intracranial and paranasal sinus
lesions, avoiding the sequelae of a skin incision, facial
bone flap or craniotomy, and brain retraction,

3. • Continued advances in surgical technique,
navigation systems, endoscopic imaging
technology, and robotics assure continued
brisk evolution in this expanding field

4. • The history of endoscopic skull base surgery is de
facto the history of pituitary surgery. The first
pituitary operation was likely performed by Sir
Victor Horsley in 1889 via a transfrontal approach
though he did not publish his results
• Schloffer who is widely regarded as the father of
modern pituitary surgery. In 1906 he published a
seminal paper discussing the possibility of
pituitary surgery via a transsphenoidal approach
and performed this operation on March 16, 1907.

5. • Then in 1910, Oskar Hirsh otolaryngologist,
introduced a transseptal, transsphenoidal
approach to the pituitary gland , an operation
which is still in use today.
• Cushing performed his first pituitary operation
in 1909 using Schloffer's method but then
rapidly adopted Hirsh's approach adding a
sublabial incision and a headlamp to improve
visualization of the sella.

6. • Hardy's contributions led to a paradigm shift
in pituitary tumor surgery. Previously, the
operation was performed to debulk large
tumors off the optic apparatus, but now
microsurgical techniques were introduced
allowing for surgical cure of hormonal disease
in microadenomas.

7. contributions
• The first endoscope is credited to Philipp Bozzini, a German
physician, who demonstrated the "Lichtleiter", a candlelit
tube, in 1806 to the Academy of Medicine in Vienna
• This was vastly improved in 1877 by Max Nitze, a German
urologist, with the addition of lenses for magnification and
an internal light source noting "to light up a room one must
carry the lamp inside ." His first endoscope used a water-
cooled platinum wire for illumination.
• Edison's invention of the incandescent bulb in 1879 allowed
the development of a cystoscope that no longer required
water cooling. Using his invention, Nitze was the first
person to perform endoscopic surgery with wire loops and
to take endoscopic pictures.

8. • The next technological breakthrough occurred
almost a century later when Harold Hopkins in
1960 vastly improved optical efficiency by
inserting glass rods and neutral gas between
the lenses.
• Basil Hirschowitz, an American
gastroenterologist, developed a flexible
endoscope using fiberoptics.

9. • The modern rigid endoscope was invented by Karl
Storz in 1965 when he combined the optical rod
system of Hopkins and used fiberoptics to carry
illumination down to the tip of the endoscope.
This endoscope allowed radically improved
visualization offering magnified panoramic views
from the tip of a narrow caliber instrument.
• Other important developments included the
invention of computed tomography, image
guidance systems and the charged coupled device
camera.

10. • Endoscopic endonasal surgery provides access
to almost all regions of the skull base situated
anterior to the foramen magnum . Tumours
are the lesions primarily concerned, but
cerebrospinal fluid (CSF) leaks of traumatic or
other origin, certain chronic infections and
congenital malformations are also accessible
to endoscopic surgery.

11. • Regions of the skull
base situated in the
midline and accessible
to endoscopic surgery
• olfactory cleft
• planum sphenoidale,
• sellar region,
• clivus,
• cervico-occipital
junction.

12. • 1: transfrontal;
• 2:transcribriform;
• 3: transplanum;
• 4: transsellar;
• 5: transclival;
• 6:transodontoid

13. LEVELS OF SKULL BASE SURGERY
• Level 1 • Sinonasal surgery
• Level 2 • Pituitary surgery
• • CSF leaks
• Level 3 • Extradural • Transcribriform
• • Transplanum
• • Transorbital (extraconal)
• • Transclival
• • Transodontoid
• Level 4 • Intradural A. With cortical cuff • Transplanum
• • Transcribriform
• • Type I craniopharyngiomas
• B. Lack of cortical cuff • Transorbital (intraconal)
• • Transplanum
• • Transcribriform
• • Type II/III craniopharyngiomas
• • Transclival intradural
• Level 5 • Cerebrovascular surgery A. Middle and posterior coronal
• planes
• B. AVM/Aneurysms

14. • Illustration showing the skull base
in an inferior view.
• module of expanded endonasal
approach at the skull base. CP-AF
= coronal plane anterior fossa;
• CP-MF = coronal
• plane middle fossa;
• CP-PF = coronal plane posterior
fossa;
• TC = transclival (pink area); TC =
transcribriform (white area);
• TO = transodontoid;
• TP/T =
transplanum/transtuberculum;
• TS = transsellar.

15. • The growing interest of neurosurgeons in this
“minimally invasive” surgery is due to the
major progress made over recent years: a
large number of anatomical studies, variants
and innovations in exposure techniques and
especially reconstruction have been reported.
Constant progress in imaging, navigation
systems, and instrumentation has also largely
contributed to the growth of this surgery.

16. • A major criticism of endoscopic techniques is
that they do not allow en bloc resection of the
tumour.
• complete resection of the zone of insertion:
tumours often present an exophytic growth
into paranasal sinuses from a smaller pedicle

17. • endonasal approach often allows resection
without damaging adjacent healthy tissues,
which is not the case with conventional open
surgery, in which the skin, bone, and
sometimes dura mater are opened to provide
access to the tumour, with a risk of tumour
seeding.

18. Instrumentation
• videoendoscopy equipment and standard endonasal
instrument
• endoscopic endonasal skull base surgery may require the
use of dedicated instruments
• The microdebrider facilitates exposure time, particularly
ethmoidectomy, and can also be used for resection in some
cases, or at least for tumour dissection .
• Some authors propose the use of ultrasonic surgical
aspirators (Dissectron®, Cavitron®) for tumour dissection,
and ultrasonic bone curettes have also been recently
developed .
• motors equipped with long handpieces allow drilling of the
thickest portions of the skull base.
• Angled burrs are particularly useful in the frontal sinus
region .

19. • haemostasis systems mainly comprise
sheathed monopolar cautery and bipolar
forceps. Diode laser is also useful, particularly
during mucosal dissection
• navigation systems are widely available and
are very useful for intraoperative anatomical
localization;
• some authors propose the use of a Doppler
probe to localize large vessels

20. • An endoscope without irrigation system has a
much smaller diameter and is therefore easier to
use and is less traumatic to the nasal cavity.
• A simple stream of saline from a syringe delivered
by the assistant onto the shaft of the optic
endoscope allows rinsing of the endoscope when
it is soiled.
• long, small-calibre dedicated instrumentation
facilitates soft tissue dissection and intradural
surgery

21. CRIBRIFORM LESIONS
• olfactory groove meningioma
• esthesioneuroblastoma,
• adenocarcinoma,
• squamous cell carcinoma,
• sinonasal undifferentiated carcinoma
• mucosal melanoma and others.

22. TRANSCRIBRIFORM APPROACH
• Defined by the removal of the cribriform plate to approach skull
base.
• This approach extends anteriorly from the posterior ethmoidal
arteries upto the level of the crista galli and frontal sinus.
• The limits are
 both laminae papyraceae laterally,
 the frontal sinus anteriorly
 the transition with the planum sphenoidale posteriorly at the level
of the posterior ethmoidal arteries

23. CONTRAINDICATIONS
 There are potential surgical limits laterally, posteriorly, and
superiorly.
LATERALLY- the midorbital plane -Removal of the lamina papyracea
enables the displacement of the orbital soft tissues to provide
access to the orbital roof laterally.
Lesions that present a lateral extension beyond the midorbit meridian
should not be accessed with a pure endonasal approach.
POSTERIORLY—the optic chiasm and anterior cerebral circulation.
Tumors lateral to the optic nerves should not be resected from a
midline endonasal approach.
Very tall tumors-difficult to access and care must be taken not to
remove too much of the inferior and anterior capsule before the
apex of the tumor has been debulked.

24. SURGERY
High-concentration adrenaline soaked cottonoids (1:1000) are placed
in the nasal cavity for 10 minutes before the surgical procedure
begins. The septum is infiltrated with lidocaine with adrenaline
1:100,000.
Nasoseptal flap created & preserved
First, the intranasal portion of the tumor - debulked to the plane of the
skull base to define the attachment to the cribriform plate, and this
attachment is cauterized with bipolar electrocautery.
Complete sphenoethmoidectomy performed bilaterally
Nasal septum transected along the sagittal plane from the crista galli
to the sphenoid rostrum approximately 1 cm inferior to the tumor
attachment to the septum.
This defines the inferior resection margin.

25. • The tumor-devascularized by cauterizing and
transecting the anterior and posterior ethmoidal arteries
The bone of the anterior cranial base in the periphery of
the tumor – thinned to the resection margins, anteriorly
to the posterior table of frontal sinus, posteriorly to the
planum sphenoidale, and laterally to the medial orbital
walls.
The thinned bone-gently fractured and elevated
inferiorly off the overlying dura.

26. • The dura - cauterized and incised longitudinally
along the lateral orbital margins, taking care to
avoid injury to cortical vessels.
 The crista galli – removed , & attached falx
cauterized and transected- facilitates rotating the
dural specimen posteriorly
Dural incision along its posterior margin allows
removal of the entire dural specimen en bloc .

27. When indicated, the olfactory bulbs and nerves are
elevated inferiorly off the overlying brain and transected
at the level of the posterior dural margin.
 Surgical defect extends from the posterior table of the
frontal sinus to the planum sphenoidale & to the medial
wall of the orbit on either side.
Surgical defect closed by nasoseptal flap
Small ipsilateral tumors- ipsilateral resection of the
anterior cranial base with preservation of olfaction on
the contralateral side can be done.

29. Advantages
• improved cosmesis,
• reduced brain manipulation,
• lower morbidity,
• shorter surgical time,
• quicker recovery and shorter hospital stay,

30. Large olfactory groove
meningioma
• (A) Preoperative (coronal)
• B) Axial section close relation of tumor to anterior
cerebral arteries at the proximal A2 segment.
• (C) Intraoperative- The right lamina papyracea
removed to expose the periorbita and provide
access to the orbital roof. The anterior and
posterior ethmoidal arteries coagulated and
sectioned to expose the anterior skull base and
provide early devascularization of the tumor.
• (D) Intraoperative- Once the tumor has been
extensively debulked, gentle extracapsular
dissection is performed.
• (E) Postoperative-T1-weighted MRI (coronal
section) complete resection
• of the tumor, cribriform plate, and crista galli. The
anterior skull
• base reconstructed with the nasoseptal flap.
• (F) Postoperative FLAIR sequence MRI (axial
section) showing nearly complete resolution of the
signal changes and minimal encephalomalacia.

31. COMPLICATIONS
• Worsening of vision.
• Intraoperative injury to A2 - it eventually led to a subsequent
pseudoaneurysm
• Bleeding associated with permanent neurologic deficits.
• CSF leak- decreased significantly as a vascularized nasoseptal
flap used for reconstruction.
• Pulmonary embolus/deep venous thrombosis
• Seizures
• Pituitary dysfunction
• Bacterial meningitis
• Myocardial infarction
• Loss of olfaction (preserved in cases of unilateral resections )

32. TRANSPLANUM /TRANSTUBERCULUM
APPROACH
INDICATIONS
Lesions involving the posterior aspect of the
anterior skull base and the suprasellar region.
Tuberculum sellae meningiomas
Giant pituitary adenomas
Craniopharyngiomas
Epidermoid tumors
Rathke cleft cysts

33. (A) Pituitary macroadenoma with significant suprasellar extension. (B)
Craniopharyngioma with large suprasellar cyst above a normal sized sella.
(C) Meningioma of the planumsphenoidale(D) Meningioma of the tuberculum
sellae.

34. Endoscopically, these are accessed by
transgressing the planum sphenoidale,
tuberculum sphenoidale and/or the sella
turcica .
Hydroscopy is performed by irrigating the field
with normal saline under gentle pressure
which lifts tissues out of the way, washes away
minimal bleeding and distends the cavity to
allow for complete inspection

35. TRANSPLANUM APPROACH
• Defined by the removal of the planum sphenoidale and tuberculum
sellae to reach skull base.
• SURGICAL LIMITS-
 Laterally-The optic canals
 Anteriorly, the posterior ethmoidal arteries.
• The critical anatomic landmark is the medial optic carotid
recess.
• The most important vital structures related –
optic nerve
- ICAs
- the anterior cerebral arteries (A1,
Huebner’s, Anterior communicating and perforators).

37. ADVANTAGES
Provides the most direct route to midline lesions of the
suprasellar cistern
Do not place critical neurovascular structures between
surgeon & lesion
Obviates the need of brain retraction
Facilitates complete , b/l optic canal decompresssion without
manipulation of compressed optic nerve
Enables surgeon to remove bone from base of tumor –site for
meningioma recurrence
Allow surgeon to interrupt blood supply early in operation

38. CONTRAINDICATIONS
• Tumor extending beyond lateral limit of this module
• Patient comorbidities that preclude prolonged
anaesthesia
• Encasement of critical neurovascular structures-
not an absolute c/I but surgeon should proceed
only if he/she can safely dissect from these
structures & has the ability to address surgial
emergency (ICA injury)

39. SURGERY
• Nasoseptal flap created & preserved
• The posterior third of the bony septum is resected
and a piece of vomeric bone is harvested as a rigid
buttress for reconstruction of the skull base.
• The sphenoid rostrum opened widely
• Bilateral posterior ethmoidectomies done
• Sphenoid ostia identified & opened widely
• Mucosa of the sphenoid sinus removed
• identification of the sella, optic nerves, and ICA is
verified with frameless stereotactic image guidance

40. • The tuberculum sellae is thinned with a high-speed
diamond drill under constant irrigation till halfway
down into the sella
• The thinned bone removed & continued along the
planum sphenoidale until the underlying dura is
exposed.
• The anterior limit of resection is the fovea overlying
the posterior ethmoid sinuses and cribriform plates.
• The superior intercavernous sinus is transected to
open the suprasellar area and visualize the pituitary
stalk and optic chiasm when necessary.

41. • The dura cauterized to interrupt the blood supply to the tumor.
• Dural and bony attachments of the meningioma resected to
prevent recurrence
• The tumor capsule sharply dissected away methodically starting
with the optic nerve .
• ICA identified ( just lateral and inferior to the optic nerve) and
tumor traced to the chiasm, along the contralateral optic nerve until
the associated ICA is identified and free of tumor Important
structures such as the ACA complex,recurrent artery of Heubner,
subchiasmal perforating vessels,optic nerves, and pituitary stalk
preserved by sharp dissection off the tumor capsule.
• Arteries that may appear to be encased can often be dissected
free of the tumor
• The resection bed is examined using angled endoscopes, with
special attention paid to ensuring that the optic nerves and canals
are free of tumor

42. Four corridors -to address lesions of the
suprasellar cistern.
• The first corridor - passes in front of the optic chiasm
- for meningiomas of the planum and tuberculum
sellae.
• The second corridor - a prechiasmal approach to the third ventricle.
( between the chiasm and the ACA )
- for pathology high in the third ventricle.
• The third corridor - below the chiasm and above the pituitary gland.
- for cystic lesions arising from the infundibulum that
extend into the third ventricle.
• The fourth corridor- beneath the pituitary gland (requires superior
mobilization of the gland),
- for lesions such as
craniopharyngiomas,chordomas, and petroclival meningiomas located
behind the pituitary gland and infundibulum

43. • Surgical defect reconstructed with fat to prevent
pooling of cerebrospinal fluid (CSF) at the bony
defect- a “gasketseal” closure done – nasoseptal
flap then rotated to cover the defect, and a tissue
sealant (DuraSeal) is used to secure the multilayer
graft in place

44. COMPLICATIONS
 INTRAOPERATIVE
• Arterial / venous bleeding
• Cranial nerve injury
• Damage to pituitary gland , stalk
& hypothalamus
 POSTOPERATIVE
• CSF leak
• Meningitis
• Hematoma formation
• Sinusitis
• Synechia formation

45. • Removal of tuberculum
meningioma. Preop and
post op MRI of a tuberculum
meningioma
• resected via a transplanum
approach. In the endoscopic
view, the carotids (C) and
optic nerves (ON)

46. • Hydroscopy.
• irrigating the sella with
normal saline and
using a 45 deg
endoscope to obtain
360 deg views around
the entire periphery to
confirm no residual
pockets of tumor. (A)
The cavernous carotid
(C) and cavernous sinus
(CS) are seen. (B) View
of the floor of the sella.

47. CLIVAL LESIONS
• The major lesions of the clivus are chordomas
and chondrosarcomas
• The clivus is most easily approached
transphenoidally however the narrowing field
of view using a microscope from this anterior
approach made pterional and retrosigmoid
approaches necessary for tumors with
significant lateral extension

48. TRANSCLIVAL APPROACH
• The clivus extends from the dorsum sellae to the
foramen magnum.
• Transclival approaches - divided into partial
(superior, middle, inferior) & complete clivus
removal.
• A transclival approach provides direct access to the
brainstem and vertebrobasilar arterial system.

49. INDICATIONS
• Meningiomas
• Chordomas.
• Chondrosarcomas
• Cholesterol granulomas
• Mucocele
• Rarely, an aneurysm that cannot be treated by
endovascular means or with significant mass effect
may be accessed via this approach and clipped

50. • The upper third - related to the dorsum sellae in
the midline and the posterior clinoids in the
paramedian region-removed either intradurally via a
transsellar approach or extradurally via a subsellar
corridor by first performing a superior pituitary
transposition
• Removal of these structures can provide access to
the basilar artery and interpeduncular cistern

51. • The middle clivus - directly accessed at the
posterior aspect of the sphenoid sinus and its
resection is limited laterally by both ICAs ascending
in the paraclival areas.

52. • The lower third of the clivus- bone drilling continues
inferiorly- limited laterally by the fossa of Rosenmuller
and the torus tubarius.
• A panclivectomy can extend all the way from the
dorsum sellae and posterior clinoids up to the basion at
the foramen magnum.
• The most related structures for this module - the brain
stem, cranial nerves II, III and VI, basilar and vertebral
arteries, superior cerebellar arteries, posterior cerebral
arteries & respective perforators

53. ADVANTAGE
• Avoid any cerebral retraction
• To decrease the incidence of injury to the lower
cranial nerves.

54. CONTRAINDICATIONS
• Patient comorbidities that might preclude them from
prolonged general anesthesia;
• Unfavorable anatomy, such as small sphenoid sinus
or diminished space between the internal carotid
arteries-makes drilling the clival bone more difficult
and risky
• Lack of multidisciplinary team cooperation and
interaction
• Lack of specialized equipment/instruments

55. DIAGNOSTIC WORKUP
The physical examination- neurologic assessment
with a special focus on cranial nerve function.
 Endoscopic assessment of the nasal cavity- to
visualize any nasal lesions and document septal
integrity, deviations, and other anatomical findings.
 An ophthalmologic examination including a visual
field examination

56. IMAGING
• Coronal, axial, and parasagittal CT of the paranasal sinuses and
skull base –
• evaluate the size of the sphenoid sinus, the position of the internal
carotid artery, especially its paraclival portion, and the thickness of
the clivus in the sagittal plane.
• MRI - to demonstrate the morphology of the soft tissues , for
involvement of the carotid artery , vertebrobasilar system & dural
sinuses
• Magnetic resonance angiography (MRA) or CT angiography(CTA)-
to assess relationship between the basilar and internal carotid
arteries and the pathology to verify the functional integrity of the
circle of Willis and the extent of any carotid artery compromise, and
to differentiate an aneurysm from a tumor

57. SURGERY
 Nasoseptal flap created and preserved
• B/l ethmoidectomy performed
• The sphenoid rostrum and anterior wall of the
sphenoid sinus exposed.
• The mucosal flap is lifted until both natural sphenoid
ostia are in view.
• A wide opening of the anterior sphenoid sinus wall
created

58.  The sinus mucosa that lines the clival area reflected ,
exposing the clival bone.
 Care is taken to ensure complete hemostasis at this
point in the procedure.
 The field should be completely dry before proceeding
to the next stage of the procedure
 Clival bone fully exposed, and removed by drilling
 The limits of the clival bone removal are the floor of the
sella superiorly, the foramen magnum inferiorly, and the
internal carotid arteries and occipital condyles laterally.

59. • Exposure at the start of
drilling the clival bone. The
distance between the
internal carotid arteries is
an important factor in
determining surgical
access to this area

60.  For intradural exposure, the external layer of the dura is first
incised with a No. 11 blade.
 Bleeding in the basilar plexus not cauterized but packed with
hemostatic material
 The opening of the internal layer of the dura at the level of the
middle and superior clivus must be accomplished with great
care to avoid injury to the underlying basilar artery.
 Once the dura opened, minor bleeding is stopped by bipolar
coagulation, and finally the 0-degree endoscope carefully
introduced into the intradural space

61.  Once the anatomy is appreciated, identify the major
vessels of the posterior fossa (basilar artery and
branches, anterior inferior cerebellar artery [AICA],
vertebral arteries, superior cerebellar and posterior
cerebral arteries); the intradural course of cranial
nerves III, IV, V, and VI; the brainstem; and the
mamillary bodies.
 The cerebellopontine angle, cranial nerves VII through
XII, and retrosellar regions are best visualized with the
45-degree endoscope

62.  Meticulous dissection is required to remove the
lesion.
 At the end of the procedure, the dural defect is
sealed with fat and fascia lata, and covered with the
flap. The packing is positioned and stays for as long
as necessary.

63. • Endoscopic anatomy following
clival resection. (A)
Anatomical
• specimen demonstrating
midline structures. (B)
Corresponding
intraoperative view.
• (C) Anatomical specimen
demonstrating left
cerebellopontine angle (CPA)
using a 45-degree endoscope.
(D) Corresponding
• intraoperative view of the left
CPA

64. COMPLICATIONAS
• Cerebrospinal fluid (CSF) leakage
• Nasal bleeding
• Bleeding from internal carotid artery, intracranial
bleeding, venous bleeding,
• Cranial nerve injuries
• Infections
• Orbital hematoma
• Nasal synechia
• Nasal infection.

65. SPINOMEDULLARY JUNCTION
LESIONS(TRANSODONTOID APPROACH)
• The most common surgical lesion of this region is
odontoid pannus usually secondary to rheumatoid
arthritis.
• An endoscopic endonasal approach to this area was
first proposed by Alfieri et al. using cadaveric studies.
The first such operation was reported in 2005
• The major advantages of the endonasal route include
quicker recovery, faster return to oral alimentation,
lower incidence of velopharyngeal insufficiency
• major drawback being limitation at the caudal end of
the dissection making the procedure not available to all
patients

66. TRANSODONTOID APPROACH
Used for resection of the odontoid process in degenerative / inflammatory diseases
or to allow for exposure of the ventral medulla and upper cervical spinal cord.
• INDICATIONS
 Foramen magnum meningiomas
 To decompress the brainstem in rheumatoid arthritis patients with degeneration
of the upper cervical spine due to compressive pannus
• It is defined by the removal of the odontoid process of the axis
• The lower third of the clivus is exposed as well as the anterior arch of C1 after
dissection of the nasopharyngeal mucosa and the rectus capitis anterior
muscle.
• The arch of C1 is drilled and the odontoid process is exposed and drilled out.
• Pannus removed by sharp and blunt dissection

67. • The most vital neurovascular structures for this module
are
the vertebral arteries,
 posterior inferior cerebellar arteries (PICAs),
brain stem
 lower cranial nerves.
 The ICAs have to be considered as a risk factor as well
because occasionally they can be positioned close to
the midline in their parapharyngeal segment under the
mucosa

68. • Preoperative CT scan of a
patient with brainstem
compression secondary to
rheumatoid degeneration
(arrow). Decompression is
achieved with removal of
the odontoid process to
the body of C2 and pannus
resection

69. TRANSORBITAL APPROACH
• A transorbital approach may be used for access to
tumors located within the orbit. The dissection can
be extraconal or intraconal

70. INDICATIONS
• Resection of sinonasal lesions that are invading
the medial wall of the orbit as sinonasal
malignances
• To decompress the optic nerves in the presence
of unresectable intraconal pathologies
• To access intraconal diseases with the goal of
resection as for schwannomas, cavernomas and
meningiomas

72. ADVANTAGES
• Posterior access to pathology near the orbital apex
is excellent via an endoscopic approach. .
• Avoid disruption of the orbicularis oculi, lacrimal
pump, or canthal ligament disruption

73. SURGERY
• It is defined by the removal of the lamina papyracea or the medial
optic canals.
• Requires a wide resection of the anterior and posterior ethmoid
cells to expose the lateral wall of the sinonasal cavity.
• The surgical field is limited laterally by the lamina papyracea and
orbital apex deeply
• The most important vital structures related to this module are the
optic nerves, the anterior and posterior ethmoidal arteries and the
ophthalmic artery with its central retina artery branch.
• The ocular muscles must be well identified during surgery and
dissection can be performed in between them.
• Subconjunctival localization and mobilization of eye muscles are
extremely helpful during endonasal endoscopic procedures.

74. ENDOSCOPIC OPTIC NERVE
DECOMPRESSION
• The most common indication for endoscopic optic
nerve decompression is traumatic optic neuropathy

75. • Surgical intervention is considered if the patient fills any of the
criteria listed below:
 Fracture of optic canal on CT scan with vision less than 6/60
 Fracture of the optic canal with vision . 6/60 but the patient’s
vision deteriorates on steroids
 Vision is , 6/60 (or there is a deterioration of vision) after
48 hours of steroid treatment with probable canal injury

76. PROCEDURE
• Cotton pledgets containing adrenaline 1:1000 are
placed in the nasal cavity over the areas of surgical
access for 10 minutes before the surgical
procedure.
• The lateral nasal wall and septum are infiltrated with
1% aropin with adrenaline 1:100.000.
• An uncinectomy, wide antro-stomy combined with
anterior and posterior ethmoidectomy is performed.

77. • The antrostomy is widened superiorly to ensure that
the maxillary sinus roof can be easily seen. This
defines the orbital floor, allows easier skeletonization of
the medial orbital wall, places the infraorbital canal on
view, and is an important landmark for defining the level
of the skull base posteriorly
• Sphenoidotomy performed
• The sphenoid should be inspected and the optic nerve,
carotid artery and pituitary fossa identified

78. • Cadaveric dissection image
taken of the left sphenoid
sinus
• demonstrating the fovea
ethmoidalis (FE) and lamina
papyracea (LP).
• ON, optic nerve; CCA, anterior
genu of the intracavernous
carotid artery; L. OCR, lateral
opticocarotid recess; ISS,
sphenoid intersinus septum;
• SS, sphenoid sinus; MS,
maxillary sinus; MT, middle
turbinate

79. • The thick bone overlying the junction of the orbital
apex and sphenoid sinus known as the optic
tubercle is thinned out with burr
• blunt Freer elevator is pushed through the lamina
papyracea ,1.5 cm anterior to the junction of the
posterior ethmoids air cell(s) and the sphenoid
• The bone of the posterior orbital apex flaked off
• Once the bone over the orbital apex is removed the
bone of the optic canal is approached. Once all the
bone has been cleared off the optic canal and the
underlying optic nerve sheath is clearly visible, the

80. • The location of the ophthalmic artery should be kept in
mind. The ophthalmic artery usually runs in the
posteroinferior quadrant of the nerve
• Therefore , the nerve is incised in the upper medial
quadrantThis incision is continued onto the orbital
periosteum of the posterior orbital apex with resultant
protrusion of orbital fat
• The orbital fat covering this area of the medial rectus
muscle is thin and care should be taken to avoid
injuring this muscle
• No packs are placed on the nerve or in the sinuses.

81. COMPLICATIONS
• CSF LEAKS
• Internal carotid artery
injury
• The optic nerve sheath
(ONS) is incised to
release the optic nerve.
PO, periorbita; ISS,
intersinus septum.

82. • PETROUS APEX LESIONS
• cholesterol granuloma, chordomas,
chondrosarcomas and meningiomas
• Traditional routes to the petrous apex have included
transmastoid approaches that must navigate around
the facial nerve and part or all of the otic capsule
• middle fossa approaches that involve brain
retraction and craniotomy.
• The transsphenoidal approach can be faster and
safer but only in selected cases. Anatomic variability
in pneumatization of the temporal and sphenoid
bone along with the location of the lesion and the
carotid should be used to guide what is the best
approach.

83. • PTERYGOPALATINE AND INFRATEMPORAL FOSSAL
LESIONS
• paragangliomas, schwannomas, sphenoid wing
meningiomas, and juvenile nasopharyngeal
angiofibromas .
• A recent review on endoscopic management of
juvenile nasopharyngeal angiofibromas concluded that
the vast majority of these lesions can be managed
safely and effectively via an endoscopic approach .
• The major concerns with endoscopic surgery in this
region are the difficulty in controlling hemorrhage from
the abundant and highly variable vasculature and
difficulty in physically accessing the lesion as the
dissection proceeds more laterally .

84. Infratemporal fossa schwannoma. (A) Preop MRI of lesion. (B) Postop MRI of lesion. (C)
Endoscopic view of schwannoma. (D) Lateral dissection. (E) Internal debulking. (F)
Endoscopic view after resection demonstrating dehiscent dura and carotid..

85. • RECONSTRUCTION
• One of the major concerns in endoscopic skull base surgery
is the need for robust reconstruction of the dural defect.
• These methods utilized various materials such as dermal
grafts, acellular dermis, free mucosal grafts, cartilage, fat,
bone and fascia often in multiple layers to close defects at
the skull base.
• regardless of the material used, there was high success
with these techniques for small defects. As defects became
larger, the success of reconstruction with these techniques
decreased leading to unacceptably high rates of CSF leak in
large endoscopic skull base procedures

86. septal mucosal flap based posteriorly off the
posterior septal artery(workhorse of endoscopic
skull base reconstruction).
transposing the temporoparietal flap through the
infratemporal fossa and pterygopalatine fossa
and then endoscopically placing the flap for
reconstruction
Pericranial flaps can also be harvested
endoscopically and then transposed into the
nasal cavity via a small osteotomy at the nasion.

87. Haemostasis
• operation should start with devascularization of
the tumour pedicle.
• In some cases, devascularization is visualized by a
colour change of the tumour.
• Arterial bleeding (sphenopalatine, ethmoidal and
internal maxillary arteries) must be prevented,
whenever possible, by preventive haemostasis
procedures designed to avoid severe bleeding
with sudden retraction of proximal fragments
(responsible for dramatic retrobulbar haematoma
in the case of ethmoidal arteries).

88. • Unexpected bleeding must be treated either
by clips or by bipolar electrocoagulation, and,
in the last resort, by packing.
• Venous bleeding, particularly due to damage
of the cavernous sinus or pterygoid venous
plexus, is difficult to control by coagulation
and haemostasis can be ensured by packing
with Surgicel® (prolonged if necessaryFloseal®,
Tissucol®, or Surgicoll.
• nasal packing must be adapted to the
procedure:

89. Endonasal packing and dressings
• When nasal packs are placed at the end of
operation, they are removed on D1 and
silastic splints are removed on D10. In
children, nasal packs may need to be removed
under nitrous oxide or even general
anaesthesia.
• The nasal cavity is examined at an outpatient
visit on D10: the formation of adherent
secretions during healing can be responsible
for local superinfection,

90. Limitations of endoscopic skull base
surgery
• Anatomical limitations
• In reality, there are few anatomical limitations
to endoscopic endonasal skull base surgery:
anatomical studies have shown that most
structures encountered during endoscopic
endonasal skull base surgery can be either
resected or mobilized.

91. • One of the main anatomical limitations is the ICA.
Accidental damage to the ICA can result in
bleeding that is often impossible to control.
• In some cases, a carotid occlusion test is
performed before the operation, but sacrifice of
an ICA is associated with a major risk of
neurological sequelae.
• Zanation et al. described a mobilization
technique of the paraclival petrosal part of the
ICA: this procedure is reserved to highly skilled
operators..

92. • Cerebral involvement remains a contraindication to
endoscopic surgery for most authors .
• Optic nerve invasion is also a major limitation, as any
resection or mobilization results in permanent visual
impairment.
• orbital invasion via the inferior orbital fissure or by
effraction of periorbital tissues theoretically requires
surgical exenteration.
• The endonasal technique does not allow satisfactory
resection of lesions involving the maxilla, nasal bones.
• Finally, by definition, skin extension constitutes a
contraindication to endoscopic surgery

93. • lesion to which access is blocked by the optic
• Limitations related to the surgical technique
• .Equipment limitations
• Surgeon-related limitations The learning curve
is an important element in the development of
this surgery . Although otorhinolaryngologists
are used to working with endonasal
endoscopes, this is not always the case for
neurosurgeons, who will therefore have to
acquire these techniques.
• Sinus surgery is generally performed with two
hands, and four-hand surgery remains unusual
for most surgeons

94. THANKS